package com.pig4cloud.pigx.user.util;

import java.util.Random;

/**
 * 随机字符串生成
 */
public class StringRandom {

	/**
	 * 生成随机数字和字母
	 *
	 * @param length
	 * @return
	 */
	public static String getStringRandom(int length) {

		String val = "";
		Random random = new Random();

		//参数length，表示生成几位随机数
		for (int i = 0; i < length; i++) {

			String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num";
			//输出字母还是数字
			if ("char".equalsIgnoreCase(charOrNum)) {
				//输出是大写字母还是小写字母
				int temp = random.nextInt(2) % 2 == 0 ? 65 : 97;
				val += (char) (random.nextInt(26) + temp);
			} else if ("num".equalsIgnoreCase(charOrNum)) {
				val += String.valueOf(random.nextInt(10));
			}
		}
		return val;
	}

	/**
	 * 生成随机数字和小写字母
	 *
	 * @param length
	 * @return
	 */
	public static String getLowercaseStringRandom(int length) {

		String val = "";
		Random random = new Random();

		//参数length，表示生成几位随机数
		for (int i = 0; i < length; i++) {

			String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num";
			//输出字母还是数字
			if ("char".equalsIgnoreCase(charOrNum)) {
				val += (char) (random.nextInt(26) + 97);
			} else if ("num".equalsIgnoreCase(charOrNum)) {
				val += String.valueOf(random.nextInt(10));
			}
		}
		return val;
	}


	/**
	 * 自定义进制(0,1没有加入,容易与o,l混淆)
	 */
	private static final char[] r = new char[]{'Q', 'W', 'E', '8', 'A', 'S', '2', 'D', 'Z', 'X', '9', 'C', '7', 'P', '5', 'I', 'K', '3', 'M', 'J', 'U', 'F', 'R', '4', 'V', 'Y', 'l', 'T', 'N', '6', 'B', 'G', 'H'};

	/**
	 * (不能与自定义进制有重复)
	 */
	private static final char b = 'O';

	/**
	 * 进制长度
	 */
	private static final int binLen = r.length;

	/**
	 * 序列最小长度
	 */
	private static final int s = 6;

	/**
	 * 根据ID生成六位随机码
	 *
	 * @param id ID
	 * @return 随机码
	 */
	public static String getRandomInviteCode(long id) {
		char[] buf = new char[32];
		int charPos = 32;

		while ((id / binLen) > 0) {
			int ind = (int) (id % binLen);
			buf[--charPos] = r[ind];
			id /= binLen;
		}
		buf[--charPos] = r[(int) (id % binLen)];
		String str = new String(buf, charPos, (32 - charPos));
		// 不够长度的自动随机补全
		if (str.length() < s) {
			StringBuilder sb = new StringBuilder();
			sb.append(b);
			Random rnd = new Random();
			for (int i = 1; i < s - str.length(); i++) {
				sb.append(r[rnd.nextInt(binLen)]);
			}
			str += sb.toString();
		}
		return str;
	}

	public static long codeToId(String code) {
		char chs[] = code.toCharArray();
		long res = 0L;
		for (int i = 0; i < chs.length; i++) {
			int ind = 0;
			for (int j = 0; j < binLen; j++) {
				if (chs[i] == r[j]) {
					ind = j;
					break;
				}
			}
			if (chs[i] == b) {
				break;
			}
			if (i > 0) {
				res = res * binLen + ind;
			} else {
				res = ind;
			}
		}
		return res;
	}
}
